investigating the effect of different acidity caused … · 2013-07-12 · it is known that when a...
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INVESTIGATING THE EFFECT OF DIFFERENT ACIDITY CAUSED BY DIFFERENT SPOONS
ON THE VOLUME OF SACCHAROMYCES ROSEI FORMED.
Extended Essay (Biology)
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ABSTRACT :
It is known that when a vegetable such as tomato is pickled, certain volume of mold,
fungi is formed. On the other hand when a metal spoon Is used instead of a wooden one, the
volume of fungi is less. This might be because, when a metal and acid (vinegar solution in the
pickle juice) reacts, H2 gas is released and the dissolving of this H2 gas results in a decrease in
pH. It should be stated that the kind of fungi formed ‘Saccharomyces Rosei’ can only
reproduce in an optimum pH of 6 to 7. But when a metal reacts with the pickle juice, the pH
will be lower than the optimum value for the ‘Saccharomyces Rosei’ thus fungal
reproduction will be inhibited to some extent. The objective of the study was to investigate,
whether the brand of spoon used made a significant difference in the volume of fungi
formed. In order to test the effect of silver nitrate, nickel, plastic and wood, 4 different data
sets of 3 trials were created as well as a control group and observed for 14 days. After 14
days, it was statistically significant that less volume of fungi was formed in the data set
containing nickel samples, when compared with the other data sets including the control
group.
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Table of Contents
Page
Introduction……………………………………………………………………………………………………. 1
Research Question………………………………………………………………………………………….. 4
Hypothesis………………………………………………………………………………………………………. 5
Method and Development……………………………………………………………………………… 6
Method……………………………………………………………………………………………………………. 8
Data Collection………………………………………………………………………………………………… 10
Analysis……………………………………………………………………………………………………………. 14
Conclusion and Evaluation………………………………………………………………………………. 16
Appendices
Appendix 1 …………………………………………………………………………………………. 19
Appendix 2 …………………………………………………………………………………………. 21
Bibliography…………………………………………………………………………………………………….. 29
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INTRODUCTION :
Every year, I hear my mom talk about the fungi she saw on the pickle jars. What is the
reason for the formation of a coat of organisms on top of the jar of a pickled vegetable? I
decided to test the effect of the usage of metal spoon with pickles on the amount of
organism, in this case an anaerobic fungi formation. This subject came to my mind after I
heard from a friend that if one used a metal spoon instead of a wooden spoon while dealing
with the pickles, they would last longer and the formation of mold on the top part of the jar
would be prevented. After the moment that I heard such theory, I became curious and
decided to test it for my own. So I started to be more careful and choose my utensils with
more attention and used a metal spoon instead of a wooden spoon when dealing with
pickled food.
As we all know, environments with a high amount of acidity are not convenient for
organisms like fungi to either reproduce or live. And when an acid reacts with a metal, it
produces salt and hydrogen1. The increase in the amount of hydrogen dissolved in the pickle
juice, causes the solution to become more acidic, in other words it lowers the pH of the
solution.
The nature of a solution based on its acidity is described as pH. The pH scale is from
0, strongly acidic, to 14, strongly basic. Neutral solutions have a pH of 7.2 Most fungi,
including Saccharomyces rosei, require near neutral conditions for optimal growth with a pH
of approximately 6.0.3 Many organisms change the pH of their substrate by producing by-
products during growth. They can change conditions such that the environment can no
longer support their growth. When the concentration of ethyl alcohol is 18%, the rate of
alcoholic fermentation decreases. Yeasts and molds are more tolerant of lower pH than the
bacteria.4
According to this, since we know that vinegar is an acid, we can’t say that this
environment is not convenient for fungal growth. The pH of vinegar is approximately 2,4.5
But when we disturb the acidity of the solution by inserting a metal, in this case the spoon,
different ionic salts and hydrogen atoms can be obtained.
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Metal + acid salt + H2 (g)
And when the produced hydrogen atoms dissolve in the water of the pickle juice, as
the concentration of hydrogen increases the pH decreases. This causes the solution to
become more acidic and according to the literature value, Saccharomyces rosei can’t
reproduce and live in such low pH.6
On the other hand, when a wooden or plastic spoon is used instead of a metal one,
none of these processes is expected to take place, thus the formation of mold, other
organisms and reproduction of possible pre-existing fungi or other organisms is not
prevented. Since there are no fungi or any other organisms present in the pickle sample
which is disturbed with a metal spoon, both the life length and the quality increases.
Different kinds of metals such as silver and nickel have different effects on the
acidity change of a pickled tomato under the same temperature, pressure conditions, when
a reaction is provided in a closed container which is permeable to light thus the amount of
fungi is expected to vary since fungal growth is effected by the hydrogen concentration,
acidity, of the environment.
Vegetables such as cabbage, unripe melon, cucumber, carrot, green pepper, beet and
tomato have been pickled for a long time in order to prevent them for rotting and save them
for later usage. The reason why I choose tomato is that tomato doesn’t contain any metal
ions such as silver or nickel within itself and it is peeled, cut into small pieces and then
pickled unlike cucumber and cabbage7. By this way it is easier for the pickle juice to diffuse
inside the pieces of vegetable, in this case the cubic tomatoes. There are several benefits of
using pickled tomatoes in this experiment. One of these benefits is that they can be divided
and cut into smaller pieces which will increase the surface area suitable for diffusion.
Besides, there aren’t any extra metal ions inside tomatoes and this allows the examination
of only the extra substance that we insert.8 Since there won’t be any reaction other than we
allow, we will not attain misleading data.
I chose to use silver and nickel as my metals because both silver and nickel can be
used to plate kitchen appliances. Despite the metals, I choose to use wood and plastic as my
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other variables since both plastic and wood aren’t expected to react with acids found in
pickles.
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REASEARCH QUESTION :
Is the volume of Saccharomyces rosei, which is responsible from the mildewing of
‘Solanum lycopersicum’9, affected by different spoons which lead to different acidity when
they react with the pickle juice under same temperature and pressure conditions?
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HYPOTHESIS :
Saccharomyces Rosei is a type of fungi which can reproduce in an optimum pH of 6 to
7. Even though, vinegar which inserted into the pickles when the pickles are being set, since
the amount very small, it doesn’t act as an anti-fungal vector. To prevent any fungal
reproduction in a jar of pickles, the pH of the environment should be disturbed and should
be turned into an acid. The pH of a solution depends on the concentration of hydrogen ions
present. This is the point where the effect of a metal comes in. It is proven that, when a
metal reacts with an acid in a neutralization reaction, both a salt is produced and hydrogen
gas is released, and when the released hydrogen gas is dissolved in the solution, the pH of
the environment decreases and the acidity increases. When the pH of the pickle juice
solution decreases, it no longer suits the optimum pH range of the Saccharomyces Rosei so
reproduction stops, at least decreases to a level. Thus I am expecting to see the minimum
amount of fungi in the falcons which I store with metals and the maximum amount of fungi
in the control group and the test groups which I stored with wood and plastic pieces since
there won’t be any interaction between these substances and pickle juice itself.
It can be hypothesized that, since the volume of Saccharomyces Rosei is dependent
on pH and since the pH is dependent on the reaction between an externally inserted
substance and the pickle juice itself, the volume of fungi formed depends on the different
spoons which lead to different acidity when they react with the pickle juice. Moreover, the
maximum volume is expected to be observed in the cases where no reaction between the
pickle juice and the spoon occurs, and the maximum volume in the cases in which metals will
be used since there will be a reaction.
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METHOD AND DEVELOPMENT :
Designing an appropriate method in order to support or reject the proposed
hypothesis and answer the given research question brought many problems with it. The first
problem was about how I was going to keep the amount of garlic, lemon juice, amount of
salt and the size of tomatoes I was going to put into little containers in which I was going to
insert different substances to test constant. This problem was solved when I decided to peel
each tomato and cut them into small cubic pieces, of about 1cm3, which were approximately
the same size and pickled these small pieces of tomatoes not in each little jar, in which I was
going to do my experiment, but in a big common jar. In order not to have a problem while
trying to equalize the amount of salt, garlic and lemon juice each experimentation jar is
containing, I put 6 grams of garlic 3 milliliters of lemon juice and 50 milliliters of water in the
common jar to prevent the tomatoes from rotting according to the recipe. I assumed that
the juice I take and put in the falcons will contain equal amounts of each because before I
divided the solution, I shook the jar in order to obtain a homogenous solution.
After pickling the tomatoes in the common jar I will put it in a cool environment
approximately 15⁰C in order to prevent it from rotting and in order to prevent the formation
of fungi until I separate it into the falcons for experimentation. Because it is known that the
optimum pH for reproduction of Saccharomyces Rosei is 30⁰C to 65⁰C. 10
The second major problem was about what kind of container I was going to use.
There was a possibility that the metal lid of glass jars would restrain the reliability of the data
collected, so glass jars with metal lids couldn’t be used. This problem was overcome when,
by further research, I found about sterile, see through, graduated 50mL falcon tubes. These
sterile falcon tubes had lids too, which was beneficial for preventing any sort of air flow or
escaping of any possibly formed gas from the environment. The labels on the container
made observing the amount of mold formed in each container easier. Labeling the
containers was essential in order to prevent any kind of confusion. Since the containers
were see through there was no need to open the containers every now and then to observe
any kind of change, and taking photos became easier.
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Not disturbing the pickles and preventing them from any possible vibration was an
additional problem. Any kind of vibration was prevented by the usage of a rack placed on a
small coffee table. I put my falcon tubes in this rack.
The amount of substance inserted was controlled by keeping the surface area of
these substances constant. Besides keeping the amount of substance constant, the amount
of pickle itself and its juice was kept constant by putting 3 cubes of pickled tomato and filling
the falcon tubes until the juice level reached 35mL. (See method) After I put 3 cubes of
tomatoes in each falcon, I am planning to use a small syringe to fill the falcon up to the 35
milliliter line so that the volume of Saccharomyces Rosei formed will be suitable for
observation, because if I use less pickle juice, the volume of fungi will also decrease
proportionally and I will have difficulty in collecting data.
It became important to make sure that all variables were being controlled. Light
intensity, temperature and pressure was kept constant for all the containers just by putting
them into the same rack and placing them in a room with no direct sunlight and with slightly
higher temperature than the average room conditions which will possibly increase the rate
of reaction. Another thing which had to be kept constant was the surface area of the
solution in contact with the air within the tube. To ensure that the surface in contact with
the air within the tube was the same, the tubes were placed inside a rack, perpendicular to
the ground.
I planned to measure the dependent variable, in this case the amount of mold
formed, by using the milliliter lines present on each falcon. By this way I will be able to
compare the volumes of Saccharomyces rosei formed. I am planning to keep the duration of
my experiment at least two weeks because reproduction of Saccharomyces rosei takes a bit
time. I will photograph the falcons once every two days because I don’t expect to observe
any distinguishing difference over a day. I decided to continue my experiment until I attained
same results in my two consecutive observations.
I am planning to have three trials for each test group, so it will be easier for me to
compare and comment on the data I have collected. Repeating the experiment for more
than once, will also give me the opportunity to use the mean values for each data set, when
evaluating my results.
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METHOD :
Materials and Apparatus :
• A big glass jar with a plastic lid
• A knife
• 3 tomatoes
• Garlic (6 grams)
• 3ml Lemon juice
• 50 ml of water
• Salt
• 15 x 50ml sterile falcon tubes
• 3 equal pieces from a plastic spoon (±2cm²)
• 3 equal pieces from a wooden spoon (±2cm²)
• 3 equal pieces of nickel (±2cm²)
• 6 grams of silver nitrate
• A permanent marker
• 15ml Syringe
• Heat source (central heating unit)
• Toothpick
• A bench top rack for 50mL falcon
To begin with, the tomatoes are washed, peeled and cut into small cubic pieces.
These pieces are placed inside the big jar and 2 cloves of garlic, each about 3 grams, are
added besides 3mL’s of lemon juice. After the pickles are ready the lid is tightly closed and
the jar is placed in a cool dark environment, approximately 15ºC, in this case in the
basement until the tomatoes were pickled. The jar is never opened for approximately 10
days after it is put in a cool and dark place.
After the tomatoes were pickled, 3 cubes of tomatoes are placed inside the sterile
tubes by the help of toothpicks and the tubes were filled with pickle juice until the 35mL
point by the help of a 15ml syringe. The tubes were divided in to 5 groups (silver nitrate,
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nickel, wood, plastic, control group) and the tubes were placed inside the bench top rack. A
different predetermined variable was put in each set of tubes, in one of the groups, nothing
was added, it was made the control group and the lids were tightly fastened and labeled
according to the substance they contained.
The rack was then placed close to a heater with normal light. The tubes were
observed and were pictured once two days to make observing the amount of mold formed
easier. I kept taking the pictures of the graduated falcons and noting down the volume of
mold until I got an identical data in two consecutive measurements in all of the categories.
When it came to measuring the amount of mold formed, I used the milliliter lines
present on each falcon. So I was able to calculate the amount of mold formed in volumes. I
repeated this experiment 3 times.
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DATA COLLECTION :
The substances which were inserted into each
falcon for experimentation for 14 days
Wood
(±0.5
cm2)
Plastic
(±0.5
cm2)
Silver
Nitrate
(±0.5 ml)
Nickel(±0.5
cm2)
Control
Group
Volume
of Mold
in
milliliters
(±0.5)
Day 0 Trial 1 0.0 0.0 0.0 0.0 0.0
Trial 2 0.0 0.0 0.0 0.0 0.0
Trial 3 0.0 0.0 0.0 0.0 0.0
Day 2 Trial 1 0.0 0.0 0.0 0.0 0.0
Trial 2 0.0 0.0 0.0 0.0 0.0
Trial 3 0.0 0.0 0.0 0.0 0.0
Day 4 Trial 1 1.0 1.5 1.5 0.5 1.5
Trial 2 1.5 1.0 1.5 0.0 1.5
Trial 3 1.0 1.0 1.0 0.0 1.0
Day 6 Trial 1 2.0 2.5 2.5 0.5 2.5
Trial 2 2.5 2.5 2.5 0.5 3.0
Trial 3 2.5 2.0 2.5 0.5 2.0
Day 8 Trial 1 3.0 3.5 3.5 1.0 3.5
Trial 2 3.5 3.0 3.5 1.0 4.0
Trial 3 3.5 2.5 3.0 0.5 2.5
Day 10 Trial 1 4.0 4.5 4.5 1.5 4.0
Trial 2 4.0 3.5 4.5 1.0 4.5
Trial 3 4.5 3.0 4.0 1.0 3.5
Day 12 Trial 1 5.0 5.0 5.5 1.5 5.0
Trial 2 5.0 4.5 5.0 1.5 5.0
Trial 3 5.0 4.5 5.0 1.5 4.0
Day 14 Trial 1 5.0 5.0 5.5 1.5 5.0
Trial 2 5.0 4.5 5.0 1.5 4.0
Trial 3 5.0 4.5 5.0 1.5 5.0
Table 1 : The table representing the change in the volume of mold, for each trial of each test
group and the control group, at each measurement in milliliters.
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The substances which were inserted into each falcon for
experimentation for 14 days
Wood (±0.5
cm2)
Plastic (±0.5
cm2)
Silver Nitrate
(±0.5 ml)
Nickel (±0.5
cm2)
Control
Group
Trial 1 5.0 5.0 5.5 1.5 5.0
Trial 2 5.0 4.5 5.0 1.5 4.0
Trial 3 5.0 4.5 5.0 1.5 5.0
Table 2 : The table representing the final volume of mold in each trial of each externally
inserted substance in milliliters (±0.5) at the end of 14 days.
The substances which were inserted into each falcon for
experimentation for 14 days
Wood (±0.5
cm2)
Plastic (±0.5
cm2)
Silver Nitrate
(±0.5 ml)
Nickel(±0.5
cm2)
Control
Group
Mean value
of the final
volumes of
mold in ml
(±0.5)
5.0
4.67
5.17
1.5
4.67
Table 3 : The calculated mean values of the volume of mold formed for every test group and
control group in milliliters.
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Standard Error Calculation :
SE = SD = ±
The substances which were inserted into each falcon for
experimentation for 14 days
Wood Plastic Silver Nitrate Nickel Control
Group
SD 0.00 0.29 0.29 0.00 0.58
SE 0.00 0.17 0.17 0.00 0.33
Table 4 : The table representing the calculated standard error and standard deviation values
for each externally inserted substance and the control group in milliliters.
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Graph 1 : The graph representing the amount of mold formed in each falcon for each trial
with the standard error calculations in milliliters.
Graph 2 : The graph representing the average amount of mold formed in each test group
and control group with the standard error calculations in milliliters.
0
1
2
3
4
5
6
7
wood plastic silver nitrate nickel control group
The
amou
nt o
f mol
d fo
rmed
in m
illili
ters
in
each
tria
l
test groups and the type of spoon pieces they contain
sample 1
sample 2
sample 3
0
1
2
3
4
5
6
wood plastic silver nitrate nickel control group
The
aver
age
amou
nt o
f mol
d fo
rmed
in
mill
iter
s
test groups and the type of spoon pieces they contain
mean
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ANALYSIS :
• The Student’s t-Test
The substances which were inserted into each falcon for
experimentation for 14 days
Wood Plastic Silver Nitrate Nickel Control
Group
SD 0.00 0.29 0.29 0.00 0.58
SE 0.00 0.17 0.17 0.00 0.33
# of samples 3 3 3 3 3
Table 5 : The table representing the standard deviation, mean calculations of the 5 data sets
and the number of trials conducted in each of these individual data sets.
Null Hypothesis (HO) : There is no effect of external substance. The differences in the data
sets are the results of chance variation only and they are not really different.
t = Df = n1 + n2 – 2
L1 : Wood
L2 : Control
Group
L1 : Plastic
L2 : Control
Group
L1 : Silver
Nitrate
L2 : Control
Group
L1 : Nickel
L2 : Control
Group
t value -1.00 0.00 -1.34 9.5
Level of significance (p) 0.05 0.05 0.05 0.05
Degrees of freedom (df) 4 4 4 4
Table 6 : The comparison of each test group with the control group by using student’s T test.
The critical value of ‘t’ for 4 degrees of freedom is : 2.13 at P= 0.05
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• 95% Confidence Interval
95%CI = SE x tP(n-1)
The substances which were externally inserted into each
falcon
Wood Plastic Silver Nitrate Nickel Control
Group
SE 0.00 0.17 0.17 0.00 0.33
# of samples 3 3 3 3 3
Value of ‘t’
at n-1
4.303 4.303 4.303 4.303 4.303
95% CI 0.00 0.73 0.73 0.00 1.42
Table 7 : The calculated 95% CI values for each data set.
• Analysis of Variance Between Groups (ANOVA)
Source SS df MS F P
Treatment 27.9 4 6.975 69.75 <.0001
Error 1 10 0.1
Ss / Bl
Total 28.9 14
Table 8 : Comparison of each data set with the help of anova calculation
The critical value of ‘F’ for 4 degrees of freedom for 15 samples is : 5.86 at P= 0.05
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CONCLUSION AND EVALUATION :
The aim of this experiment was to show that, the usage of different brands of spoon
could also be the reason for the formation of colonies of Saccharomyces rosei on top of a jar
of pickled tomato. I started this experiment out, by deciding what may be one of the human
based reasons, which caused the pickles to become moldy faster. When I heard from a
friend that, there was a common belief, that the pickles became moldy slower, when a metal
spoon was used when the pickles were being served. I learnt that people preferred a metal
spoon instead of a wooden one to prevent the pickle from molding. To test whether the
usage of a metal spoon made an obvious difference or whether it was just a rumor, I planned
an experiment. I decided to measure the amount of mold formed in a constant amount of
pickle with different brands of spoon. I put equal amounts of pickled tomato and it’s juice
and placed equal sized plastic, wood, nickel and silver nitrate pieces in different falcons. The
reason why I choose plastic, wood, nickel and silver was because these materials can be used
to make spoons. I placed the falcons in same and convenient conditions for fermentation
and watched them carefully and took notes. After 16 days, the data I was collecting became
stationary and I was able to make a comment on them.
According to my hypothesis, I was expecting to see the lowest volume of mold in the
falcons which contained the metals silver nitrate, nickel ;and; the highest volume of mold in
the falcons which I either put wood, plastic or the falcons I labeled as my control group. As it
can be seen in table 1, the data I have collected supported my hypothesis.
As a result of the calculations in which I compared the data sets of wood, plastic, and
silver nitrate with the control group, my “t” value was smaller than that of the expected “t”
value which corresponded to the level of significance value of p= 0.05 and to the degree of
freedom value of df=4.
Opposing to this, the “t” value I calculated when I was comparing the data sets of
nickel and the control group was bigger than the literature value of “t” at p= 0.05 and df=4.
According to the rules of the student’s “t” test, if the t value calculated is smaller than
the literature value of the “t” value required, we accept the suggested null hypothesis (H0)
but on the other hand, if the calculated “t” value is greater than the literature value, we
reject the null hypothesis and except the firstly suggested hypothesis.
Under the light of these facts, I can say that, for the data sets of wood, plastic and silver
nitrate, we except the suggested null hypothesis. The differences in the data were the
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results of chance variation and that they weren’t actually affected by the external substance.
But for the nickel data set, we can’t reject the null hypothesis, and we except that the
external substance had a remarkable effect.
Analysis of variance between groups (ANOVA) is used when the result of an
experiment consist of more than two mean values. ANOVA is better and more relevant
compared to the student’s “t” test. Because in the students t test we except on error of
0.05% in each comparison and as the number of data sets we deal with increases,
determining the total error becomes almost impossible. But in the case of ANOVA, since we
only do a single calculation, it’s easier to determine the error.
After the ANOVA calculation, I found my F value to be 69.75 and I saw that my
expected F value for 15 samples and at 4 degrees of freedom was equal to 5.86 at a level of
significance of p=0.05. Just as in the student’s t test, if the calculated F value is greater than
the literature value we reject the suggested null hypothesis. But according to my
calculations, I saw that my F value was bigger than the literature value, so we reject the null
hypothesis and conclude that, in at least one of the cases, the effect of the external
substance was observed and that the differences in the results didn’t rise from chance
variation. And according to the t-test results shown in table 7 and mean results in table 3, I
conclude that the case in which I found that the effect of external substance was important,
is the data set of Nickel.
The volume of mold formed in all of the trials were close to each other in the cases of
wood, plastic, nickel and in the control group. But in the case of silver nitrate, the data was
not reliable. This resulted from the fact that silver nitrate was used instead of silver. Since
silver nitrate precipitates when it reacts with salt (salt (NaCl (aq)) is present in pickle juice),
using silver nitrate was a mistake, since it didn’t act as a metal inside the pickle, it just
precipitated and turned into an irrelevant salt AgCl.
AgNO3 + NaCl AgCl + NaNO3
Secondly, since I conducted the whole experiment in my house, I wasn’t able to carry
out the experiment with full success. I wasn’t able to keep the temperature constant, since
the central heating system was working on determined time intervals. In order to solve this
problem an incubator could be used to keep the temperature of the experimentation
environment constant at a specific temperature.
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Third of all, before I started to test the effect of different substances on the pickles, I
cut tomato pieces of 1 cm3 size and waited for them to be pickled in a common jar. But
during the period of time they waited in that jar, their edges may have melted away, which
may have caused a change in the surface area of the tomatoes. By this way, the area where
diffusion can occur decreased and this may have led to a decrease in the volume of mold
formed. To prevent any possible surface loss, the tomatoes should either be pickled first and
then cut into 1cm3 pieces, or they can be grated first and then pickled.
Fourth of all, when I was taking the falcons from the rack, to take their photographs,
the pickles in the falcons shook, and some of the mold formed mixed with the juice and
disappeared. In order to prevent any mold loss, separate and see through racks should be
used for each data set. And these racks should be placed on a smooth surface to prevent the
falcons from any possible vibration.
After I filled the falcons, when I was closing their lids, some amount of oxygen gas
was left in the falcons. Since Saccharomyces rosei is a fungus which does anaerobic
respiration, the presence of oxygen inside the falcons may have inhibited the respiration of
the fungi to some extent, and this may have resulted in formation of less mold compared to
the mold we would get if the experiment was conducted in an oxygen proof falcon. To
overcome this error source, after filling the falcon, liquid oil can be poured inside the falcon
until the surface of the pickles is covered. By this way the interaction of oxygen and fungi can
be prevented.
We do not have any idea about the metal percentages in the spoons we use at home
since they are alloys. Thus we can’t be sure which metal contributed to the formation of
mold and which metal didn’t. To be sure of this, pure silver, pure nickel etc. should be used.
Lastly I was only able to do 3 trials for each substance inserted. If there were more
trials, I would have been able to talk about more definite facts.
For further experimentation, one can test the effect of the metal which was inserted
into the pickles in the first stage of pickling.
Since the temperature of the environment has a positive effect on the rate of
reaction, one can question why the pickles aren’t being stored in refrigerators.
Other than these, one can also conduct this experiment with different vegetables and
without any external substances, so see the amount of contribution of the ions found
internally in the vegetables to the amount of mold formed.
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APPENDICES :
• APPENDIX 1 : Statistics Tables
t table with right tail probabilities
df\
p 0.40 0.25 0.10 0.05 0.025 0.01 0.005 0.0005
1 0.32492
0
1.00000
0
3.07768
4
6.31375
2
12.7062
0
31.8205
2
63.6567
4
636.619
2
2 0.28867
5
0.81649
7
1.88561
8
2.91998
6 4.30265 6.96456 9.92484 31.5991
3 0.27667
1
0.76489
2
1.63774
4
2.35336
3 3.18245 4.54070 5.84091 12.9240
4 0.27072
2
0.74069
7
1.53320
6
2.13184
7 2.77645 3.74695 4.60409 8.6103
5 0.26718
1
0.72668
7
1.47588
4
2.01504
8 2.57058 3.36493 4.03214 6.8688
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F Table for alpha=.05 .
df
2/
df
1
1 2 3 4 5 6 7 8 9 10 12 15 20 24 30 40 60 12
0
IN
F
1
16
1.
44
76
19
9.
50
00
21
5.
70
73
22
4.
58
32
23
0.
16
19
23
3.
98
60
23
6.
76
84
23
8.
88
27
24
0.
54
33
24
1.
88
17
24
3.
90
60
24
5.
94
99
24
8.
01
31
24
9.
05
18
25
0.
09
51
25
1.
14
32
25
2.
19
57
25
3.
25
29
25
4.
31
44
2
18
.5
12
8
19
.0
00
0
19
.1
64
3
19
.2
46
8
19
.2
96
4
19
.3
29
5
19
.3
53
2
19
.3
71
0
19
.3
84
8
19
.3
95
9
19
.4
12
5
19
.4
29
1
19
.4
45
8
19
.4
54
1
19
.4
62
4
19
.4
70
7
19
.4
79
1
19
.4
87
4
19
.4
95
7
3
10
.1
28
0
9.
55
21
9.
27
66
9.
11
72
9.
01
35
8.
94
06
8.
88
67
8.
84
52
8.
81
23
8.
78
55
8.
74
46
8.
70
29
8.
66
02
8.
63
85
8.
61
66
8.
59
44
8.
57
20
8.
54
94
8.
52
64
4
7.
70
86
6.
94
43
6.
59
14
6.
38
82
6.
25
61
6.
16
31
6.
09
42
6.
04
10
5.
99
88
5.
96
44
5.
91
17
5.
85
78
5.
80
25
5.
77
44
5.
74
59
5.
71
70
5.
68
77
5.
65
81
5.
62
81
5
6.
60
79
5.
78
61
5.
40
95
5.
19
22
5.
05
03
4.
95
03
4.
87
59
4.
81
83
4.
77
25
4.
73
51
4.
67
77
4.
61
88
4.
55
81
4.
52
72
4.
49
57
4.
46
38
4.
43
14
4.
39
85
4.
36
50
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• APPENDIX 2 : Photographs
Figure 1 : Test group of silver nitrate at day ‘0’.
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Figure 2 : Test group of silver nitrate at day ‘6’.
Figure 3 : Test group of silver nitrate at day ‘14’.
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Figure 4 : Test group of nickel at day ‘0’.
Figure 5 : Test group of nickel at day ‘6’.
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Figure 6 : Test group of nickel at day ‘14’.
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Figure 7 : Test group of wood at day ‘0’.
Figure 8 : Test group of wood at day ‘6’.
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Figure 9 : Test group of wood at day ’14’.
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Figure 10 : Test group of plastic at day ‘0’.
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Figure 11 : Test group of plastic at day ‘6’.
Figure 12 : Test group of plastic at day ‘14’.
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Figure 13 : Control group at day ‘0’.
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Figure 14 : Control group at day ‘6’.
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Figure 15 : Control group at day ‘14’.
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